A person smokes a Juul Labs Inc. e-cigarette in this arranged photograph taken in the Brooklyn Borough of New York, U.S.

Gabby Jones | Bloomberg | Getty Images

Tobacco stocks dipped Wednesday after the Food and Drug Administration said it was investigating nearly three dozen cases of people who had seizures after vaping.

The FDA said that between 2010 and 2019 it received 35 reports of people, especially teens and young adults, experiencing seizures after using e-cigarettes. Severe nicotine poisoning can cause seizures. However, the FDA said it's unclear whether e-cigarettes caused the seizures in these cases.

Shares of Altria, which late last year invested $12.8 billion for a 35 percent stake in e-cigarette giant Juul, fell nearly 5 percent. Shares of British American Tobacco traded in the U.S. slid nearly 3 percent. Shares of U.K.-based Imperial Brands traded in the U.S. dipped 4 percent.

Even though the FDA didn't directly blame e-cigarettes, the news won't help the already negative perception surrounding the devices. A study published last week from researchers at Georgia State University found the proportion of adults who think e-cigarettes are as bad as or worse than combustible cigarettes increased substantially over five years.

The news may also spook investors who are already fearing the FDA will tighten e-cigarette restrictions even more as it tries to control what the agency has labeled an "epidemic" of teen vaping.

For more on investing in health care innovation, click here to join CNBC at our Healthy Returns Summit in New York City on May 21.